JPH0825037B2 - Method for detecting butt angle of ERW pipe - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for detecting a butt angle of an electric resistance welded pipe.

[Prior Art] In the production of ERW pipe, as shown in FIG.
The butt shape (angle) of both edge surfaces 2 of the material 1 is I
By setting the V-converging points (points at which two facing materials contact each other for the first time) on the inner surface side 3 and the outer surface side 4 of the shell to be the same, the heat input and the upset amount can be adjusted in the plate thickness direction (vertical direction). ) Is desirable. On the other hand, when the abutting shapes of the end surfaces 2 on both ends of the material 1 are the V-shape shown in FIG. 1B or the inverted V-shape shown in FIG. 1C, the inner surface side 3 and the outer surface side 4 of the blank tube 4 The V convergence point position does not match in the plate thickness direction (vertical direction), and the heat input and upset amount are 3 on the inner surface side.
Also, there is a problem that the outer surface side 4 becomes non-uniform and welding defects are likely to occur.

Therefore, in the production of electric resistance welded pipes, the abutting angles of both edge surfaces of the material (the angle formed by the both edge surfaces of the material facing each other, θ in FIG. 1 (b) or θ ′ in FIG. 1 (c)). Accurately knowing online is extremely important. From such a viewpoint, the technique described in Japanese Utility Model Laid-Open No. 55-559135 or Japanese Patent Laid-Open No. 57-139480 has been known.

That is, in the former, in the production of electric resistance welded pipes, the temperature difference between the inner surface side and the outer surface side welded part (bead) is detected, and the temperature difference corresponds to the abutting angle of both end edge surfaces of the material. The butt angle is detected based on. Also, the latter irradiates the welding light on the inner and outer surfaces with slit light and detects the height of each weld bead from each light cutting profile. Since it corresponds to the butt angle of the surface, the butt angle is detected based on the detection result.

However, such a method has the following problems. That is, in the former case, when the temperature measurement position is close to the welding point (V convergence point), the temperature of the molten steel at the welded portion is measured, the measured temperature is saturated, and the temperature difference between the welded portions on the inner surface side and the outer surface side is It cannot be detected, and the butt angle of both edge surfaces of the material cannot be detected. On the other hand, if the temperature measurement position is far from the welding point, the temperature of the bead after solidification, which has already decreased in temperature, will be measured, and the butt angle of the edge surfaces of both ends of the material cannot be accurately detected. Further, the welding point position changes depending on the welding conditions (heat input amount, upset amount, pipe forming speed, etc.), and it is difficult to specify the position. That is, since it is difficult to obtain a measurement position that accurately obtains the temperature difference between the inner surface side and the outer surface side that exactly corresponds to the abutting angle of both end edges of the material, the method that uses the welding temperature as a parameter is not accurate. It was difficult to detect a good butt angle.

In the latter case, the shape of the weld bead is not only greatly changed by the outer diameter and plate thickness of the raw pipe or the welding conditions (heat input force, upset amount, pipe making speed, etc.) associated therewith, but also spatter is generated. Since the bead amount decreases randomly, it was difficult to detect the butt angle with high accuracy for a wide range of outer diameters and plate thicknesses or welding conditions (heat input force, upset amount, pipe forming speed, etc.) associated therewith. .

[Problems to be Solved by the Invention] The present invention is to detect a butt angle when manufacturing an electric resistance welded pipe, and to eliminate welding conditions due to a defective butt angle.

[Means for Solving the Problems] The gist of the present invention is a camera installed above the welding point of an electric resistance welded pipe, and measures the distance between the double lines of the corners of the edge surfaces of both ends of the material that is red-heated by the heat input from the welding. Then, the butt angle detection method of the electric resistance welded pipe is characterized in that the butt angle of both edge surfaces of the material is detected by the distance between the double lines.

That is, the both end edge surfaces of the material in the electric resistance welded portion are red-hot due to welding heat input, but as shown in FIG. 2, the welding current has two corner portions, that is, the inner surface side 3 and the outer surface side 4 of the edge surface 2. Since it concentrates on the wire, when observed with a camera installed above the weld, the double line (a,
Observed as b). _Let E _{a be} the distance between the double lines measured from the image obtained by the camera and t be the wall thickness of the material being ERW welded, and the edge surface of the material and the center line C of the viewing direction of the camera being observed. _The angle θ _a formed with a can be obtained by the equation (1) as shown in FIG.

θ _a = sin ⁻¹ (E _a / t) (1) Then, the reference line H of the line and the center line C _{a of the} camera in the visual field direction
When the angle a .theta.C _a forming angle .theta.E _a formed by the reference line H and the substrate edge surface of the line, as shown in FIG. 5, (2)
It can be obtained by a formula.

_{θE a = θC a + θ a} = θC a + sin -1 (E a / t) ... (2) both end edge surface of the material, the angle between the reference line H of the line, measured singly by detection methods, θE _a , θ
If you obtain E _b , the butt angle θ
Can be obtained by the equation (3) as shown in FIG.

θ = θE _a −θE _b = [θC _a + sin ⁻¹ (E _a / t)] − [θC _b + sin ⁻¹ (E _b / t)] (3) The present invention has been made based on the above findings. The characteristic of this is that in the ERW pipe production line, the camera installed above the welding point measures the distance between the double lines of the corners of the edge surfaces of both ends of the material that has red heat due to the welding heat input. It is to detect the abutting angle of both edge surfaces of the material by the interval of.

The present invention will be described below with reference to exemplary embodiments shown in the drawings. FIG. 7 is an example of installation of a camera for measuring the distance between the double lines at the corners of the both end edge surfaces of the material and a control device for controlling the abutting of the both end edge surfaces of the material for carrying out the present invention. FIG. As shown, a pair of left and right squeeze rolls 9a, 9
Predetermined pressure is applied to material 1 by b, while squeeze roll 9
Contacting the contact tip 11 to the material 1 in front of, and supplying the high frequency current from the high frequency oscillator 12 to the material through the contact tip 11, thus heating, pressurizing and welding the butted portion of the material 1. Tube 1a
Is formed. 9c and 9d are top rolls. Cameras 13a (for observing the left edge) and 13b (for observing the right edge) are cameras for measuring the distance between the double lines at the corners of both edge surfaces of the material.

As described above, was determined from an image obtained by these cameras, double line spacing E _a (left edge) of the corner portions of both end edge surface of the material, and E _b (right edge), the viewing direction of the camera The angle between the center lines C _a (when observing the left edge) and C _b (when observing the right edge) and the reference line H of the line θC _a (when observing the left edge) and θC _b (when observing the right edge) By performing the calculation using the equation (3) in the analysis device 14 from the wall thickness t, the abutting angle θ of the both end edge surfaces of the material is detected.

θ = θE _a −θE _b = [θC _a + sin ^-1 (E _a / t)] − [θC _b + sin ^-1 (E _b / t)] (3) The abutting angle θ of both edge surfaces of this material The detection result is input to the control device 15 for controlling the abutting of both edge surfaces of the material.

[Effects of the Invention] As described above, in the present invention, the distance between the double lines of the corners of the edge surfaces of both ends of the material that is red-heated by the welding heat input is measured by the camera installed above the welding point. By doing so, it is possible to detect the butt angle of the edge surfaces of both ends of the material easily and extremely accurately. Also, because the camera is installed above the weld,
Since the visual field failure due to spatter is unlikely to occur, the reliability of the apparatus is high, and the number of stoppages in the manufacturing line for maintenance of the detection apparatus is extremely small. This greatly contributes to stable product quality and reduced manufacturing cost without impeding productivity.

[Brief description of drawings]

FIG. 1 (a) is a view showing a butted portion of the material in the case of I type, FIG. 1 (b) is the case of the same V type, and FIG. 1 (c) is a view of the same inverted V type, Fig. 2 is a cross-sectional view of the welded portion showing an example of a state in which two corners of both edge surfaces of the material are red-heated by welding heat input, and Fig. 3 shows the welded portion shown in Fig. 2 installed above. Fig. 4 shows an example of double lines at the corners of the edge surface of the material obtained when observing from the direction 5 with the above-mentioned camera. Fig. 4 shows the edge surface of the material and the center line of the viewing direction of the observing camera. Fig. 5 shows that the angle formed by is determined by the distance between the double lines observed by the camera and the wall thickness of the material. Fig. 5 shows that the angle between the reference line of the line and the edge surface of the material is the reference line of the line. The angle between the center line of the camera and the view direction of the camera, and the view direction of the camera observed with the edge surface of the material shown in FIG. Fig. 6 shows that it is determined by the angle formed by the core wire, and Fig. 6 shows that the abutting angle of both end edges of the material is determined from the angle formed by the reference line of the line shown in Fig. 5 and each of the left and right edge surfaces. FIG. 7 (a) is a side view of the line showing an example of an apparatus for carrying out the present invention, and FIG. 7 (b) is a front view of the same line. a ... Left edge outer surface corner portion, b ... Left edge inner surface corner portion, c ... Right edge outer surface corner portion, d ...
Right side edge inner surface side corner portion, 1 ... material, 2 ... edge surface, 3 ... inner surface of element pipe, 4 ... outer surface side of element tube, 6 ... material moving direction, 7 ... sectional position of FIG. 2, 9 ... squeeze roll ,Ten
… Contact chip, 11… High frequency oscillator, 12… Camera,
13 ... Analysis device, 14 ... Control device, 15 ... Material movement direction.

Claims (1)

[Claims] 1. A camera installed above a welding point of an electric resistance welded pipe,
It is characterized in that the distance between the double lines at the corners of the edge surfaces of both ends of the material that is red-heated by welding heat input is measured, and the butt angle of both edge surfaces of the material is detected by the distance between the double lines. How to detect the butt angle of the sewing pipe.